Replies

1. 
   Routerman | Aug 17, 2007 08:36pm | #1

   Thread on a no. 10 is ~3/16". Pilot Hole for sheet metal, cap screw & wood screws is safe @ 13/64".

   Would not expect this to offer much slop for X-grain humidity changes.

    

   Routers

1. 
   JMadson | Aug 18, 2007 01:55am | #3

   Just to confirm the logic my Dad taught me...

   The pilot hole should match the shank size of the screw, right?  

1. 
   Routerman | Aug 18, 2007 02:47am | #4

   Pilot = the hole in the stick that receives the head of the screw. That hole should be = or > than the thread diameter. You don't want any thread biting ino that piece.

   Now then, the hole for the threaded section of the screw (sometimes called a thread hole) is related to the root or shank as you call it. What size? Depends on type of screw and material it is going into.

   In soft wood drill to  ~ the root diameter for wood & sheetmetal screws.

   In hard hard wood: No <~5/32 (for a no.10)

   In metal: It varies.

   Key here is to have some slop in the hole for the screw thread in stick no.1 and drill for the thread as tight as practical in stick no.2. This is not B&W & when in doubt drill a couple of sample holes in the project stock & test. Have cracked many boards following charts and other jive protocols.

    

2. 
   doorboy | Aug 17, 2007 11:59pm | #2

   I googled 'pilot hole sizing chart' and got a few bites.
   In this instance, 1/8" should do fine.

   Two guys walk into a bar, a third guy ducked.
3. 
   mrbird90 | Aug 18, 2007 03:10am | #5

   The shank hole (clearance hole for unthreaded section of screw) should be 3/16" in dia, and the pilot hole should be 1/8" for hard wood and 7/64" for soft wood. The pilot hole is in the wood that the screw is screwed into.

   
   

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   Edited 8/17/2007 8:11 pm ET by mrbird90